Ultrafast Stark-Induced Polaritonic Switches

Abstract

A laser pulse, several meV red-detuned from the excitonic line of a quantum well, has been shown to induce an almost instantaneous and rigid shift of the lower and upper polariton branches. Here we demonstrate that through this shift, ultra-fast all-optical control of the polariton population in a semiconductor microcavity should be achievable. In the proposed setup a Stark field is used to bring the lower polariton branch in or out of resonance with a quasi-resonant continuous-wave laser, thereby favoring or inhibiting the injection of polaritons into the cavity. Moreover we show that this technique allows for the implementation of optical switches with extremely high repetition rates.PACS numbers: 42.50. Pq, 42.79.Ta, 71.36.+c Systems made of quantum wells embedded in semiconductor microcavities, where light and matter are strongly coupled, provide a versatile area for the study of fundamental physics and new states of matter such as outof-equilibrium polariton condensates. Due to the strong non-linear interaction between polaritons, they also have great potential for the implementation of next-generation all-optical computational technologies. Moreover, the very short lifetime of cavity-polaritons can in principle guarantee extremely fast operation rates. For these reasons, in recent years significant efforts have been devoted to the dynamical control of polaritonic systems and several proposals have been made to implement switches, spin-switches, transistors, and resonant tunneling diodes on cavity-polariton systems [1-9].The general idea underlying all these proposals is to use exciton-exciton/polariton-polariton interactions to control the blueshift of the lower-polariton branch directly with the driving laser and, in this way, to manipulate the number of polaritons in a given spatial location and given energy state of a microcavity. The main disadvantage of this technique is that when the duration of the laser pulses used to trigger the desired operations is in the sub-picosecond regime, the corresponding bandwidth is of the order of the Rabi splitting of the system. Therefore, the effect of short pulses is not only to inject polaritons, but also to excite exciton reservoirs with relatively long lifetimes that relax into polaritons and considerably slow down the dynamics of the system. As a result, the dynamical control of polariton systems has not yet reached the ps or sub-ps regime.Instead, the idea underlying the present work is to shift the energy of the polariton branches using the Stark effect produced by a laser far red-detuned from the excitonic line. It has been recently shown [10] that the dynamic Stark effect can be used to shift both the lower polariton (LP) and the upper polariton (UP) branches almost rigidly, with the shift lasting only for the duration of the Stark pulse (typically less than a ps). This ultra-fast control is possible because the Stark pulse does not excite reservoirs of long-lived particles.In this letter, we propose a setup where a continuouswave laser (CW) is used to r...

Spin Textures of Exciton-Polaritons in a Tunable Microcavity with Large TE-TM Splitting

“…These spin textures can be described as orthogonal eigenstates on the higher order Poincaré sphere (HOPS) [41]. This might lead to a new type of cavity quantum eletrodynamics by manipulating the vector states on the HOPS involving both the OAM and polarization (pseduospin) degrees of freedom, since the excitonic part of the polaritons can be dynamically manipulated with external magnetic field or fast Stark pulses [42,43].…”

Nonlinear spectroscopy of exciton-polaritons in a GaAs-based microcavity

“…Concerning applications operating in the THz frequency range, oscillations of the polariton population due to the dynamic Stark effect [25,26] and relaxation oscillations [27] have been observed, but unambiguous evidence for THz-lasing operation is still lacking. For an evaluation of the feasibility of the proposal of Ref.…”

Operation speed of polariton condensate switches gated by excitons

“…An on-off transition time of a few picoseconds, but the reversal off-on transition time still being in the hundreds of picoseconds, has been reported for resonant injection of polaritons in the lower polariton branch, avoiding the generation of excitons [4]. Ultrafast shifts of the lower and upper polariton branches exploiting the Stark effect in microcavities [37] have been proposed to implement optical switches with high repetition rates [5]. Furthermore, one can envision more complex geometries where, instead of excitons, polaritons flowing in a crosswise direction are employed to create the gate barrier.…”

“…Their comparatively lighter mass makes the condensation easier regarding the temperature [2]. Optical devices incorporating such condensates are promising candidates for new ultrafast, low-power consuming information processing components [3][4][5]. Different structures, including one-dimensional ones, have been proposed recently for the realization of transistors [6,7], diodes [8], optical routers [9], spin current controllers [10], logic gates [11], and for building a universal set of logic AND-and NOT-type gates [12].…”